Passive magnetic elevator car steadier

ABSTRACT

A device ( 22 ) for damping vibrations between a first component ( 16 ) and a second component ( 14 ) includes a receiving member ( 24 ) configured to be connected to the first component ( 16 ), a first permanent magnet ( 26 ) arranged inside the receiving member ( 24 ), a second permanent magnet ( 28 ) arranged inside the receiving member ( 24 ) in series with the first magnet ( 26 ), and an engaging member ( 30 ) slidably connected to the receiving member ( 24 ) and including a first end configured to engage the second component ( 14 ) and a second end inside the receiving member ( 24 ) adjacent the first magnet ( 26 ). The second magnet ( 28 ) includes a pole which repels a facing pole of the first magnet ( 26 ).

BACKGROUND

The present invention relates to damping vibrations between first andsecond components. More particularly, the invention relates to apermanent magnet damper configured to dampen vibrations transmitted toan elevator car from guide rails on which the car rides.

A typical elevator system includes an elevator car and a counterweight,each suspended on distal points on hoist ropes in an elevator hoistway.In some systems, the elevator car is attached to a car frame to whichthe hoist ropes are attached. The elevator system also includes guiderails extending the length of the hoistway and attached to oppositesides of the hoistway. A group of roller guides are attached to theelevator car or car frame and guide the car or frame up and down thehoistway along the guide rails.

There are several factors that impact the quality of the elevator carride in elevator systems. One such factor is the total length of thehoistway. Longer hoistways require a greater number of guide railsegments stacked within the hoistway and a greater number of jointsbetween the guide rail segments. A greater number of guide rail segmentsresults in greater total weight of the guide rails. The increased weightof the guide rail segments causes the rails to deflect in the hoistway.Also, the joints between the guide rail segments result indiscontinuities at the joints. Even slightly deflected rails and minimaldiscontinuity in joints cause an ascending or descending elevator car tovibrate and move laterally.

To minimize the adverse impact of rail imperfections on the ride qualityof the elevator car, roller guide assemblies commonly include asuspension system and a damping system. However, prior roller guideassemblies have struggled with balancing the stiffness required fordamping and the cushion required for suspension. In addition to rollerguide suspension and damping, prior elevator systems have commonlyemployed crude rubber bumpers arranged between, for example, the frameand the car to steady the car during operation. These bumpers are oftenmounted and adjusted incorrectly, leading to increased vibration in theelevator car. The material properties of the bumpers degrade over timeand therefore necessitate relatively frequent replacement. Finally, thebumpers transmit vibrations, for example from the car frame to the car,which excites other components thereby generating additional noise inthe system.

Prior elevator systems have also employed electromagnetic couplers toreduce the impact of guide rail imperfections on the ride quality of theelevator car. However, electromagnetic couplers have severaldisadvantages. Electromagnetic couplers are subject to failure when thepower source driving the electromagnets included in such couplers fails.Electromagnetic couplers consume extra electric energy during operationand increase the mass added to elevator systems employing such couplers.In addition, electromagnetic couplers are very costly, practicallyprohibiting their use in commercial elevator systems applications.

In addition to active solutions such as the electromagnetic coupler,elevator systems including passive non-contacting permanent magnetcouplers have been proposed. One such coupler is described in PCTInternational Application No. US2007/002433, entitled “Permanent MagnetNoise Isolator.” Non-contacting magnetic couplers, such as described inPCT US2007/002433, may be employed to physically isolate the elevatorcar from vibrations caused by guide rail imperfections. The magneticcouplers include groups of repelling magnet pairs arranged to form acoupling between, for example, the elevator car and the car frame or thecar frame and the roller guides.

In light of the foregoing, the present invention aims to resolve one ormore of the aforementioned issues that afflict elevator systems.

SUMMARY

A device for damping vibrations between a first component and a secondcomponent includes a receiving member configured to be connected to thefirst component, a first permanent magnet arranged inside the receivingmember, a second permanent magnet arranged inside the receiving memberin series with the first magnet, and an engaging member slidablyconnected to the receiving member and including a first end configuredto engage the second component and a second end inside the receivingmember adjacent the first magnet. The second magnet includes a polewhich repels a facing pole of the first magnet.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory only,and are not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become apparent from the following description, appendedclaims, and the accompanying exemplary embodiments shown in thedrawings, which are hereafter briefly described.

FIG. 1 shows an elevator system.

FIG. 2 shows an elevator system including an embodiment of a permanentmagnet damper according to the present invention.

FIG. 3 is a detail perspective view of a set of the dampers shown inFIG. 2 arranged at a junction between the car frame and the top of thecar.

FIG. 4 is a section view of one embodiment of the permanent magnetdamper shown in FIGS. 2 and 3.

FIG. 5 is a graph of the repulsive force of the permanent magnets in adamper similar to the permanent magnet damper of FIGS. 2-4 versus thedistance between the magnets.

FIG. 6 is a detail top view of an alternative embodiment of the presentinvention in which the number and arrangement of the permanent magnetdampers in the elevator system is modified.

DETAILED DESCRIPTION

Efforts have been made throughout the drawings to use the same orsimilar reference numerals for the same or like components.

FIG. 1 shows an elevator system 10, which includes traction members(e.g., cables, as shown, or alternatively belts) 12, a car frame 14, acar 16, roller guides 18, and guide rails 20. The cables 12 areconnected to the car frame 14 and a counterweight (not shown) inside ahoistway. The car 16, which is attached to the car frame 14, moves upand down the hoistway by force transmitted through the cables 12 to thecar frame 14. The roller guides 18 are attached to the car frame 14 andguide the car frame 14 and the car 16 up and down the hoistway along theguide rails 20.

Imperfections in the guide rails 20 may affect ride quality by causingthe car frame 14, and thereby the car 16, to vibrate and move inside thehoistway. There are several factors that impact the ride quality of thecar 16. As previously discussed, two factors are: (a) the total lengthof the hoistway, which directly correlates to the potential for thesegments of the guide rails 20 to deflect; and (b) the potential fordiscontinuities in the joints between the segments of the guide rails20. Even slightly deflected and discontinuous guide rails 20 causevibrations or noise, which may be transmitted through the roller guides18 and the car frame 14 to the car 16.

FIG. 2 shows an elevator system 10 including one embodiment of permanentmagnet damper 22 according to the present invention. In FIG. 2, elevatorsystem 10 includes the car frame 14, the car 16, the roller guides 18,the guide rails 20, and twelve permanent magnet dampers 22 (eight ofwhich are shown in FIG. 2). The dampers 22 may be connected to the topand bottom of the car 16 adjacent the car frame 14. The dampers 22connected to the top of the car 16 may include, for example, two sets ofthree dampers 22 located at the two junctions between the car frame 14and the top of the car 16. Each damper 22 is positioned to counteractagainst another damper 22 with which it is aligned, thereby defining adamper pair. In the shown embodiment, for the dampers 22 provided at thetop of the car 16, a first pair of dampers is provided in a first of thetwo sets of three dampers 22, a second pair of dampers is provided inthe second of the two sets of three dampers 22, and a third pair ofdampers is defined by one damper 22 provided in the first set of threedampers 22 and one damper 22 provided in the second set of three dampers22.

FIG. 3 is a detail perspective view of one set of three dampers 22arranged at one junction between the top of the car frame 14 and the topof the car 16. This set of dampers 22 includes one damper pair 22 a, 22b; the other damper 22 c is paired with a damper in another set ofdampers 22. Each pair of dampers 22, for example the dampers 22 a and 22b shown in FIG. 3, may be arranged in opposition to dampen vibrationsbetween, for example, the car frame 14 and the car 16 in two directionsin one dimension (e.g., forward/backward directions, side-to-sidedirections, and/or up-and-down directions). Referring again to FIG. 2,the dampers 22 may be configured to dampen vibrations caused byimperfections in the guide rails 20 and transmitted from the rollerguides 18 to the car frame 14, and from the car frame 14 to the car 16.By arranging the dampers 22 between the car 16 and the guide rails 20,in this embodiment at the four connections between the car frame 14 andthe car 16, the car 16 may be substantially isolated from disturbancescaused by the guide rails 20. For example, in the elevator system 10shown in FIG. 2, imperfections in the guide rails 20 caused by slightdeflections or discontinuities cause the roller guides 18, and therebythe frame 14 to deflect or vibrate as the guides 18, the frame 14, andthe car 16 ride along the guide rails 20. However, the car 16 may besubstantially unaffected by such imperfections in the guide rails 20,because the dampers 22 between the car frame 14 and the car 16 may actto substantially absorb the vibrations caused by the guide rails 20before reaching the car 16.

FIG. 4 is a section view of one embodiment of the permanent magnetdamper 22, which includes a receiving member in the form of a sleeve 24,a first magnet 26, a second magnet 28, an engaging member such as aplunger 30 journalled in the sleeve 24, a threaded member such as a bolt32 and a buffer such as an O-ring 34. The damper 22 is either fastenedto a base 40 or integrally formed along with the base 40. As shown inFIG. 3, the base 40 and, therefore, the damper 22 may be connected (byfasteners 42 such as bolts) to a first component, for example the car16, adjacent to a second component, for example the car frame 14, andmay be configured to dampen vibrations between the car 16 and the carframe 14. The first magnet 26 may be arranged inside the sleeve 24 withone end adjacent the plunger 30 and another end facing the second magnet28. The second magnet 28 may be arranged inside the sleeve 24 in serieswith the first magnet 26 with one end adjacent the bolt 32 and anotherend facing the first magnet 26. The bolt 32 may be replaced with, forexample, a set screw in alternative embodiments of the presentinvention. The first and second magnets 26, 28 may be, for example,generally cylindrical. The facing ends of the first and second magnets26, 28 include repelling magnetic poles. In FIG. 4, for example, a north(“N”) pole of the first magnet 26 is facing a north (“N”) pole of thesecond magnet 28. In another embodiment of the damper 22, a south (“S”)pole of the first magnet 26 may be arranged facing a south (“S”) pole ofthe second magnet 28. The plunger 30 is slidably connected to the sleeve24 adjacent the first magnet 26. In some embodiments of the presentinvention, the plunger 30 may be made from an engineering plastic. Forexample, the plunger 30 may be made from a nylon and molybdenumdisulphide (MoS2) composition like Nylatron produced by QuadrantEngineering Plastic Products located in Reading, Pa. or an acetal resinlike Delrin produced by E. I. du Pont de Nemours and Company located inWilmington, Del. The bolt 32 is adjustably connected to the sleeve 24adjacent the second magnet 28. The bolt 32 may be configured to easilyadjust the spacing between the first and second magnets 26, 28.Moreover, although not shown, a locking mechanism may be provided toprevent the bolt 32 from being backed-out of the sleeve 24 due to therepulsive force between the first and second magnets 26, 28.

In operation, vibrations and deflections of the car frame 14 cause thecar frame 14 to engage the plunger 30 of the damper 22. The damper 22dampens the vibrations and deflections as motion of the plunger 30 intothe sleeve 24 is resisted by the repelling magnetic fields of the firstand second magnets 26, 28. The repulsive force of the magnetic fieldsfrom the first and second magnets 26, 28 is proportional to the distancebetween the magnets, thereby increasing the damping effect of the damper22 as the plunger 30 is pushed further into the sleeve 24.

Additionally, in embodiments in which the sleeve 24 is electricallyconductive, the motion of the first magnet 26 may act to induce an eddyelectrical current in the electrically conductive sleeve 24. Electricalcurrent induced in the sleeve 24 may in turn generate its own magneticfield that may combine with the magnetic field of the first magnet 26,thereby increasing the damping effect of the damper 22 as the plunger 30continues to push the first magnet 26 toward the second magnet 28.Therefore, the repulsive force of the damper 22 may increaseexponentially as the first magnet 26 is pushed by the plunger 30 towardthe second magnet 28 inside the sleeve 24. FIG. 5 illustrates thecumulative effect of magnetic fields produced in the sleeve 24.Specifically, FIG. 5 depicts a graph of the repulsive force of the firstand second magnets 26, 28 (y-axis) versus the distance between the firstand second magnets 26, 28 inside the sleeve 24 (x-axis).

In FIG. 4, the first magnet 26, second magnet 28, and plunger 30 mayhave an air barrier 38 between and surrounding them inside the sleeve 24that contributes to the damping strength of the damper 22. The pneumaticdamping created by the air barrier 38 inside the sleeve 24 may beadjusted by changing the size of the cavity housing the first and secondmagnets 26, 28 and/or by adding one or more holes between the exteriorand interior of the sleeve 24. For example, in FIG. 4 sleeve 24 includeshole 36 with a first opening on an inside surface of the sleeve 24 and asecond opening on an outside surface of the sleeve 24. The damper 22 mayalso include the O-ring 34 configured to physically limit the travel ofthe plunger 30. The O-ring 34 may be, as shown in FIG. 4, arrangedaround a shank of the plunger 30 between a head of the plunger 20 and anend of the sleeve 24. Alternatively or additionally, an O-ring may bearranged inside the sleeve 24 between the first and second magnets 26,28.

Although FIG. 4 shows an embodiment of the damper 22 including twopermanent magnets (26, 28), embodiments of the damper 22 may include oneor more additional permanent magnets arranged in series with the firstand second magnets 26, 28 and adapted to adjust the damping strength ofthe permanent magnet damper 22. In embodiments including more than twopermanent magnets (26, 28) in series inside the sleeve 24, the magnetsmay be arranged such that facing ends of each magnet pair have repellingmagnetic poles. For example, one embodiment of the damper 22 may includethree permanent magnets arranged in series with the north pole of thefirst magnet facing the north pole of the second magnet and the southpole of the second magnet facing the south pole of the third magnet,therefore, the three magnets are arranged with a repelling poleconfiguration of (S-N)(N-S)(S-N). Similarly, another embodiment of thedamper 22 may include three permanent magnets arranged in series withthe south pole of the first magnet facing the south pole of the secondmagnet and the north pole of the second magnet facing the north pole ofthe third magnet, therefore, the three magnets are arranged with arepelling pole configuration of (N-S)(S-N)(N-S).

A variety of permanent magnets may be appropriate for use in permanentmagnet dampers according to the present invention. Permanent magnets arereadily available and come in a variety of shapes, sizes, and strengths.For example, a rare-earth magnet such as a neodymium magnet isappropriate for use in embodiments of the present invention. Neodymiummagnets are made of a combination of neodymium, iron, and boron (NdFeB)and are commercially available in cylinder, wafer, ring, ball, and tubeshapes as well as in many other shapes. Where appropriate anddepending-on the intended application, a variety of other types ofpermanent magnets, including samarium-cobalt, may be used in permanentmagnet dampers according to the present invention.

Permanent magnet dampers according to the present invention may beadapted to applications outside the elevator industry. For example,embodiments of the present invention may be adapted to dampen vibrationsbetween two components in an automobile. Furthermore, embodiments of thepresent invention similar to the damper 22 shown in FIGS. 2-4 mayfunction as a shock absorber by being configured to absorb low frequencyand high amplitude vibrations between two components.

FIG. 6 is a detail top view of an alternative embodiment of the presentinvention in which the number and arrangement of the dampers 22 in theelevator system 10 is modified. In the embodiment of FIG. 6, elevatorsystem 10 includes the frame 14, the car 16, and eight dampers 22connected between the car 16 and the frame 14. In comparison to theembodiment of FIGS. 2-4, each of the four junctions (one of which isshown in FIG. 6) includes two rather than three dampers 22.Additionally, the plunger 30 of each damper 22 is connected to, asopposed to arranged adjacent to and engaging, the frame 14.Specifically, the two dampers 22 at each junction are arranged betweenthe frame 14 and the car 16 with a common rotatable connection A betweenthe plungers 30 and the frame 14, and separate rotatable connections B,C between the car 16 and ends of the sleeves 24 opposite the commonrotatable connection A. The common rotatable connection A between theframe 14 and the plungers 30 of the two dampers 22 may be, for example,a shackle connected to the frame 14 and a clevis pin rotatablyconnecting the two dampers 22 to the shackle.

Embodiments of permanent magnet dampers according to the presentinvention and elevator systems including such dampers provide severaladvantages over prior methods and apparatuses for improving the ridequality in elevator cars. Embodiments of permanent magnet dampersaccording to the present invention may be arranged between twocomponents to substantially absorb vibrations between the twocomponents. For example, the dampers may be arranged between twoelevator system components between the elevator car and the guide railsand may be configured to dampen vibrations caused by the guide railsbefore the vibrations reach the elevator car. Further, in embodiments inwhich the permanent magnets are arranged in series, the system is notonly entirely passive, it also acts directly and instantly to an appliedload, i.e., if one element (e.g., the car frame) is exposed to a suddenlarge vibration, the permanent magnet system greatly inhibits thevibration from being passed to a second element (e.g., car) bygenerating a correspondingly large level of damping.

Embodiments of the present invention including cylindrical permanentmagnets arranged in series are less complex and costly than activesolutions such as prior electromagnetic devices and in some applicationsdisplay greater stability than prior passive magnetic arrangements.Furthermore, in elevator system applications, setup of the car and thedampers may be improved. The car may be first mounted on its loadweighing devices, and then the magnetic dampers may be released andadjusted for proper separation between the car and the frame.Misalignment of the car or imbalance of the loading results in a clearvisual indicator. The car position with respect to the frame may bequickly adjusted, for example, by adjusting the bolts included in thedampers.

The aforementioned discussion is intended to be merely illustrative ofthe present invention and should not be construed as limiting theappended claims to any particular embodiment or group of embodiments.For example, embodiments of permanent magnet dampers according to thepresent invention include modifications adapted to change thecharacteristics of the damper, such as changing the conductivity of thematerial of the sleeve, varying the thickness of the sleeve or the sizeof the cavity in which the magnets are housed, changing the size, shape,and number of magnets, changing the size of the air barrier and the holein the sleeve, and changing the shape of the buffer from an O-ring to asubstantially cylindrical resilient member. Thus, while the presentinvention has been described in particular detail with reference tospecific exemplary embodiments thereof, it should also be appreciatedthat numerous modifications and changes may be made thereto withoutdeparting from the broader and intended scope of the invention as setforth in the claims that follow.

The specification and drawings are accordingly to be regarded in anillustrative manner and are not intended to limit the scope of theappended claims. In light of the foregoing disclosure of the presentinvention, one versed in the art would appreciate that there may beother embodiments and modifications within the scope of the presentinvention. Accordingly, all modifications attainable by one versed inthe art from the present disclosure within the scope of the presentinvention are to be included as further embodiments of the presentinvention. The scope of the present invention is to be defined as setforth in the following claims.

1. An elevator system, the system comprising: a car; a car frameconnected to the car; and a plurality of permanent magnet dampersarranged to dampen movement of the car relative to the car frame,wherein each of the magnet dampers comprise: a receiving memberconnected to a first component; a first permanent magnet arranged insidethe receiving member; a second permanent magnet arranged inside thereceiving member in series with the first magnet, wherein the secondmagnet includes a pole which repels a facing pole of the first magnet;and an engaging member slidably connected to the receiving member andcomprising: a first end configured to engage a second component; and asecond end inside the receiving member adjacent the first magnet.
 2. Thesystem of claim 1, further comprising: at least one guide connected tothe car frame, wherein the magnet dampers are configured to dampenvibrations between the car and the at least one guide.
 3. The system ofclaim 1, wherein the first component is one of the car or the car frameand the second component is the other of the car or the car frame. 4.The system of claim 3, wherein the plurality of permanent magnet damperscomprises: three pairs of permanent magnet dampers connected to the topof the car adjacent the frame.
 5. The system of claim 4, wherein theplurality of permanent magnet dampers comprises: three pairs ofpermanent magnet dampers connected to the bottom of the car adjacent theframe, and wherein the two magnet dampers in each of the pairs of magnetdampers are configured to dampen vibration between the car and the framein two opposing directions.
 6. The system of claim 3, wherein thereceiving member is a sleeve and the engaging member is a plungerjournalled in the sleeve.
 7. The system of claim 6, wherein an end ofthe sleeve opposite the plunger is rotatably connected to the car; andwherein the first end of the plunger is rotatably connected to theframe.
 8. The system of claim 6, wherein the plurality of permanentmagnet dampers comprises: two pairs of permanent magnet dampersconnected between the top of the car and the frame.
 9. The system ofclaim 8, wherein the plurality of permanent magnet dampers comprises:two pairs of permanent magnet dampers connected between the bottom ofthe car and the frame, and wherein the two magnet dampers in each of thepairs of magnet dampers are configured with a common rotatableconnection between the plunger and the frame, and with separaterotatable connections between the end of the sleeve opposite the plungerand the car.
 10. The system of claim 6, wherein each of the plurality ofpermanent magnet dampers further comprises a threaded member adjustablyconnected to the sleeve opposite to the plunger and including an endinside the sleeve adjacent the second magnet.
 11. The system of claim10, wherein the end of the threaded member is connected to the secondmagnet.
 12. The system of claim 6, wherein each of the plurality ofpermanent magnet dampers further comprises an O-ring configured to limitthe movement of the plunger with respect to the sleeve, and wherein theO-ring is arranged around a shank of the plunger between a head of theplunger and an end of the sleeve to which the plunger is slidablyconnected.
 13. The system of claim 6, wherein the sleeve comprises atleast one orifice with a first opening on an inside surface of thesleeve and a second opening on an outside surface of the sleeve.
 14. Thesystem of claim 1, wherein each of the plurality of permanent magnetdampers further comprises one or more additional permanent magnetsarranged in series with the first and second magnets inside thereceiving member.
 15. The system of claim 1, wherein each of theplurality of permanent magnet dampers further comprises a bufferconfigured to limit the movement of the engaging member with respect tothe receiving member.
 16. The system of claim 15, wherein the buffer isan O-ring.
 17. The system of claim 1, wherein the receiving member isformed of an electrically conductive material such that when either orboth of the magnet(s) move within the receiving member, an eddyelectrical current is generated.
 18. The system of claim 1, wherein atleast one of the first and second magnets is generally cylindrical. 19.A device for damping vibrations between a first component and a secondcomponent, the device comprising: a receiving member configured to beconnected to the first component; a first permanent magnet arrangedinside the receiving member; a second permanent magnet arranged insidethe receiving member in series with the first magnet, wherein the secondmagnet includes a pole which repels a facing pole of the first magnet;and an engaging member slidably connected to the receiving member andcomprising: a first end configured to engage the second component; and asecond end inside the receiving member adjacent the first magnet. 20.The device of claim 19, further comprising one or more additionalpermanent magnets arranged in series with the first and second magnetsinside the receiving member.
 21. The device of claim 19, wherein an endof the receiving member opposite the engaging member is configured to berotatably connected to the first component; and wherein the first end ofthe engaging member is configured to be rotatably connected to thesecond component.
 22. The device of claim 19, further comprising athreaded member adjustably connected to the receiving member opposite tothe engaging member and including an end inside the receiving memberadjacent the second magnet.
 23. The device of claim 19, furthercomprising a buffer configured to limit the movement of the engagingmember with respect to the receiving member.
 24. The device of claim 23,wherein the buffer is an O-ring.
 25. The device of claim 19, wherein thereceiving member is formed of an electrically conductive material suchthat when either or both of the magnet(s) move within the receivingmember, an eddy electrical current is generated.
 26. The device of claim19, wherein at least one of the first and second magnets is generallycylindrical.
 27. The device of claim 19, wherein the receiving member isa sleeve and the engaging member is a plunger.
 28. The device of claim28, further comprising: an O-ring configured to limit the movement ofthe plunger with respect to the sleeve, wherein the O-ring is arrangedaround a shank of the plunger between a head of the plunger and an endof the sleeve to which the plunger is slidably connected.